You might want to look into a Think Vitamin membership (full disclosure: affiliate link). That home page heavily promotes their conferences and Q&A sessions, but they have a pretty good library of training videos, including HTML, CSS, and PHP (among other topics).

If you really want a book, I would recommend the Visual QuickStart series, especially if you learn best from seeing illustrations and doing examples.

Since you mentioned you're explicitly looking to build these skills to help you with your WordPress blog, I would start with the book WordPress: Visual QuickStart Guide from Peachpit. (You may be able to find a cheap used copy on Amazon.com too.)

If you need to extra help, you can consider their other books on XHTML, CSS, and PHP, though it's possible you won't need them.

There is also, of course, the ever popular Dummies series. WordPress for Dummies seems to be fairly nice.

I've already outgrown the basic WordPress specific books. But thanks though. I'd like to improve upon my knowledge of PHP and CSS so that I can understand the background better and also potentially building a theme at some point. Another thing is that I got an error message with one of my plugins recently. So in searching around I found that a change needed to be made to a php file of the plugin. I was able to make the edit, but I'd feel a lot more comfortable with at least some php knowledge under my belt. thanks again
–
wdypdx22Aug 17 '10 at 0:58

Ah, in that case, have you considered one of O'Reilly's books? They have "Learning PHP 5", "Programming PHP", "JavaScript: The Definitive Guide", and "CSS: The Definitive Guide", all of whom I consider must-haves for developers. I'm not sure if those are overkill for your needs, but perhaps Learning PHP 5 could be a good start.
–
Mike LeeAug 18 '10 at 7:35

Yes! In fact I did. I was at the Open Source Conference here in Portland last month and discovered that I had an O'Reilly coupon among the conference goodies. And picked up Head First PHP and MySQL. Thank you for the tips.
–
wdypdx22Aug 19 '10 at 15:28

I'd suggest reading Beginning WordPress 3 and Professional WordPress. I would not be concerned about the poor initial reviews on the first book - they are people complaining that it's too advanced, and based on your description of your knowledge level, I don't think that would be a concern. I have both books and like them both (although I have not finished them - I just purchased them).